Explore a pedagogical lecture on the Gaussian Unitary Ensemble, a fundamental random matrix model, and its connection to 2D quantum gravity and holography. Delve into the double scaling limit, the Airy model, and non-perturbative information computed using Fredholm determinants. Discover a previously unnoticed discrete spectrum and its holographic implications. Examine topics such as refinement diagrams, topological expansion, Dyson gas, semicircle law, orthogonal polynomial technology, and random surfaces. Gain insights into the development of techniques, the large N limit, and the connection between random matrices and toy field theory.